# How do you evaluate -1 - cos^2(74) - sin^2 (74)?

Jul 1, 2016

Factor out $- 1$:

$= - \left(1 + {\cos}^{2} \left({74}^{\circ}\right) + {\sin}^{2} \left({74}^{\circ}\right)\right)$

Recall the Pythagorean identity ${\cos}^{2} x + {\sin}^{2} x = 1$.

$= - \left(1 + 1\right)$

$= - 2$

Hopefully this helps!